![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png){kind=small}
Okay, so I've been playing with virtualization over the last few weeks (VMware, Virtual PC, and XEN), and I'm kind of not seeing the point.
Okay, loading up Virtual PC on my machine at home, and installing Win98 so I can play old games is nifty and all (and hey, my motherboard even has hardware support for VMs, which Vitual PC can and does take advantage of...), but the whole server virtualization thing eludes me.
I mean, how is running a bunch of VMs is any less resource intensive than running a bunch of jailed processes (or, chrooted if you're still living in the dark ages :P)? In fact, as far as I can tell, it's MORE resource intensive, since I have to dedicate hard amounts of memory to each VM, where jails just use memory as needed out of the system total. I'm going to be running the same services either way, I don't see less processor cycles used, it's more, actually since that VM's local OS has its own overhead it has to take care of.
Am I missing something here? This looks like a solution looking for a problem. I can see where it could be useful in the same way building a bootable CD/DVD to run an OS off of is useful, except less secure since the VMs disk image can be fucked with, unlike immutable optical media.
EDIT:
So, after chatting with some friends, it seems VMs make things like patching and DR easier, which I can see, and it abstracts HA out to an easier to manage level, which is nice. Still, not going to save the planet moving everything to VMs, and some things still belong on dedicated hardware (which, may mean a single host/guest arrangement if you're hardcore on doing VM everywhere, no matter what).
Okay, loading up Virtual PC on my machine at home, and installing Win98 so I can play old games is nifty and all (and hey, my motherboard even has hardware support for VMs, which Vitual PC can and does take advantage of...), but the whole server virtualization thing eludes me.
I mean, how is running a bunch of VMs is any less resource intensive than running a bunch of jailed processes (or, chrooted if you're still living in the dark ages :P)? In fact, as far as I can tell, it's MORE resource intensive, since I have to dedicate hard amounts of memory to each VM, where jails just use memory as needed out of the system total. I'm going to be running the same services either way, I don't see less processor cycles used, it's more, actually since that VM's local OS has its own overhead it has to take care of.
Am I missing something here? This looks like a solution looking for a problem. I can see where it could be useful in the same way building a bootable CD/DVD to run an OS off of is useful, except less secure since the VMs disk image can be fucked with, unlike immutable optical media.
EDIT:
So, after chatting with some friends, it seems VMs make things like patching and DR easier, which I can see, and it abstracts HA out to an easier to manage level, which is nice. Still, not going to save the planet moving everything to VMs, and some things still belong on dedicated hardware (which, may mean a single host/guest arrangement if you're hardcore on doing VM everywhere, no matter what).
Tags:
![[identity profile]](https://www.dreamwidth.org/img/silk/identity/openid.png){kind=small}
From:
Re: VMotion
From:
Re: VMotion
From:
Re: VMotion
And at some point, it fails to scale. Virtualisation gets to be really useful not at the "one dual/quad cpu intel box" level but at the Really Fuckoff Big High-Availability Machine level with lots of submachines.
The overhead from running an extra OS is surprisingly low, and it lets you run the exact OS and patchlevel that your particular app requires even if there're twenty different environments needed.
Also, it's more secure. Chroot/jail is not exactly perfect.